<!DOCTYPE html>
<html>
<body>

  <textarea id="testBox" style="padding:2px;" readonly></textarea>
  <script type="text/javascript">
    //Adding focus to the textbox should trigger a spellcheck
    var textbox = document.getElementById("testBox");
    addEventListener("load", function() {
      textbox.readOnly = false;
      textbox.focus();
      textbox.value = "blahblahblah";
      textbox.selectionStart = textbox.selectionEnd = 0;
      textbox.blur();
    }, false);
  </script>

</body>
</html>
